OUCH! I think Arnold and Sergio would totally own Ronnie if they competed today.
that's certainly debatable, but i'm talking sheerly if you compared them each as they showed up on stage at their respective peaks. if you somehow used a time machine and got them all equal playing fields it's hard to say, but that's not what i'm talking about here. arnold at 6'2" and flex at around 5'8" weigh the same, and arnie's conditioning isn't as good (remember, the whole drugs thing).
the hypotheticals of how arnie or sergio would look today are damn near impossible. i have a feeling arnie would be gunter, sergio would be ronnie.